Critique this Lift Mechanism, Please!

With all the scissor lifts sure to be seen this year, our team tried to explore each different way a scissor lift could be powered. So far, we’ve had limited success, which is a bit frustrating. One of the ways we tried to power the scissor lift was sort of a rack-and-pinion system, and it actually seemed to work really well for a while. However, now the lift is leaning towards one side and tipping each time it goes up. This could be from any number of variables (motor strength, catching, alignment, etc), but we were wondering if there was a reliable fix anyone could see. I’ve included some pictures in this post of the lift mechanism, and in the meantime are trying yet another method of powering the lift on a model drive train. Thank you guys for all the help!

For the pictures, see attachments. Sorry that they’re sideways!
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Your design seems very good, I don’t see any flaws with my naked eyes, but I suggest more testing to try to find the problem. We wish we’d have thought of this. :slight_smile:

It looks solid and stable, but one of the biggest problems that I see in the future would be weight. The wide c-channels you’re using for support could be swapped out for the thinner ones in the future. Also, the less space between the two outside bars, the better. Your’s looks good in that department though. Other than that, it all looks good! Keep up the work.

You want to push the rubber bands as close as possible to each side of the scissor lift. As you make the screws longer, the screw jabs up against the pillow block eventually creating more friction than power gained. Also since it’s powered on the bottom, you’re going to experience a lag when raising. Because of this, you’ll want to add a bit of space on top, or more rubber bands. If the leaning problem is pretty bad, make sure your screws aren’t too tight

If you really want to go for more quality, you can definitely redesign the lift to be lighter and more stable.

Looks great! The linear lift position you chose is the one that has the consistent rate of lift over the motion. It also can be one of the slowest. It works great, but be prepared to wait versus other lift designs.

These are all minor things you may run into. There is nothing majorly wrong with this design at all.

The bottom back connection looks a bit long. Any way to make that shorter? You may bend that over time.

The bottom front connections to the flat metal might start bending over time. Maybe an aluminum 1x5x1 C channel?

On the bottom front connections outside part. You may want black spacers to ensure that distance is constant. Any changes to that distance can be magnified up top when the lift is extended.

More rubber bands! Make it so the motor is almost fighting to keep the scissor down. Then you know you have enough.

Zip tie down those long wires. Figure out some means of getting them to not be easily entangled and inadvertently ripped out in heavy game play.

There’s no means of physically synchronizing the drives left and right in this design. Make sure you have potentiometers on both sides and ensure lift control through software. (harder to do)

Do you need 1x5x1 cross braces? Could 1x2x1 versions work as well? Not sure how much of a weight difference you will get.

I have never built a scissor lift before: so i cant say i know what is right or what is wrong but there is one thing i did notice. Where you have your motors mounted to lift the system (image 3), you do not have any bearing blocks supporting your axles (well i don’t see any, i could be wrong). The reason why you need those is that when a square axle rotates in a square hole, the axle tends to rub against the metal as it rotates. This causes a ton of strain on your motors and generates a ton of friction. Thus slowing down your lift.